As far as the "lose a card" method goes, maybe have that as a game mode choice. At the beginning of a match you can choose to play for cards or just play for fun. This way people know what they're getting into and aren't forced into one mode or the other. Also if someone playing for cards disconnects they should lose a card. Yes some people have unstable connections but they should know about that and should probably just play for fun unless they know their connection is going to hold up.